Licence: Public Domain Mark
Credit: Fractures and dislocations. Source: Wellcome Collection.
Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.
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![astragahts inwards or outwards, the foot is turned in the o])posite direction, and one or other malleolus is sunken, while the other one is unusually prominent. All movements of the ankle joint are abolished. Dislocation backwards.—The astragalus, in rare instances, may be forced directly backwards from all its articulations, or, what is more common, may be forced backwards and outwards, or backwards and inwards. Sometimes the injury is complicated with fracture of the -neck of the astragalus; the head of the bone then remains connected with the scaphoid, and the lai-ger portion, or body, is alone displaced. In the direct backward displacement, the under surface of the astragalus rests on the posterior part of the upper surface of the os calcis, immediately in front of the tendo Achilles, so that the posterior surface of the bone presses upon the tendon, sometimes pushing it backwards, out of its normal position. When dis- located obliquely, backwards and inwards, or back- wards and outwards, the astragalus undergoes a species of rotation as well, so that its superior surface, instead of being directed upwards, is oblique in direc- tion and looks more or less inwards or outwards, and projects under the skin between the inner or outer malleolus and the os calcis, according as the displace- ment is internal or external. Causes.—The accident is probably produced by severe violence or twists applied to the foot while in a condition of flexion. When the foot is acutely flexed on the leg, the neck of the astragalus almost reaches the anterior margin of the lower end of the tibia, and the posterior part of the bone is supported by the posterior fasciculus of the external lateral ligament, the posterior fibres of the deltoid ligament and the thin, narrow band passing between the posterior margin of the astragalus and the os calcis, which ligaments would be put on the stretch. If from](https://iiif.wellcomecollection.org/image/b21518798_0518.jp2/full/800%2C/0/default.jpg)
